Ever since the presidential coin flip of 2000, weve been hearing ad nauseam what a deeply divided nation we are. Now, it seems, were also deeply divided about how deeply divided we really are.

Bill Bishops widely discussed and thoroughly researched May series for the Austin American-Statesman was only the most recent, albeit the most comprehensive, depiction of a bifurcated America, occupied on the one hand by traditionalist, religious G.O.P. voters in rural areas and exurbs, and on the other by cosmopolitan secular liberals. Both, were told, are increasingly fiercely partisan and ever more concentrated in landslide counties where one major-party candidate takes a huge margin of the vote.

The inevitable counternarrative has finally surfaced, with a lengthy John Tierney piece in The New York Times claiming that the Red/Blue value chasm is largely a myth created by people inside the Beltway...shouting at each other. Even David Brooks, whose primary shtick is a wonkified version of the its funny how black people and white people are different act beloved of uninspired stand-ups, recently made a nod in the same direction, suggesting that our partisan polarization isnt just the upshot of some essential chasm between the Nascarites and the Lattéans, but rather inflamed or even driven by the civil war within the educated class.

One problem with the two Americas thesis is that if you take a quick glance at the core constituencies of the two parties, there sure seem to be a lot more than just two. Adrian Wooldridge, The Economists Washington, D.C., correspondent and co-author of The Right Nation, told me that at the recent 40th anniversary celebration of the American Conservative Union, I found myself thinking What do these people have in common? You have the [National Rifle Association] saying government must stay out of my gun locker at all costs, and the Family Research Council saying government must stay in peoples bedrooms at all cost, so to some extent its a coalition of convenience.

The blue-state coalition doesnt seem any more organic. Inner-city minorities, affluent urbanites and blue-collar union members  three key Democratic groups  may share a statistical metropolitan area, but its not clear this entails some kind of larger cultural continuity. Yet there is a persistent unifying force Wooldridge sees: Self-definition in opposition to an imagined other. Much as Democrats today seem less animated by enthusiasm for Kerry than hostility toward Bush, Wooldridge found among the motley crew on the right a common sense of who the enemy is: People at the A.C.U. dinner were never as happy as when they were raging against the Clintons.

In a sense, that may explain the popularity of the two Americas narrative. For reasons Ill discuss below, that sense of belonging to the same team is becoming more important as a political organizing tool. The two Americas picture confirms the worst stereotypes about the opposition shared by loose political coalitions, in effect constructing genuine opposed communities by circulating the idea of them  similar to the way the proletarians in Marxist theory were supposed to awaken to class consciousness via their discovery of shared oppression by the bourgeoisie. Perhaps ironically, campaign finance reform may have aided the process by shifting political communication resources from the relatively risk-averse parties to the political-advocacy organizations known as 527s like the MoveOn Voter Fund. Few official campaigns would run anything like the culture warmongering Club for Growth ad in which a couple declares that Howard Dean should take his tax hiking, government expanding, latte-drinking, sushi-eating, Volvo-driving, New York Times reading, body-piercing, Hollywood-loving left wing freak show back to Vermont, where it belongs.

Problematic as a stripped down binary portrait of American politics is, the elite kabuki story wont entirely work either. The germ of institutional truth in that counternarrative is that aggressive top-down gerrymandering and the bottom-up geographical self-segregation by political ideology have given candidates powerful incentives to shift their focus from persuading undecided centrist voters to a strategy of base-mobilization. That would push political rhetoric to extremes even assuming constant voter attitudes. But the idea that the appearance of vigorous partisanship is wholly some sort of epiphenomenon driven by elite conflict also rings false.

If anything, urban elites on opposite ideological sides are probably more moderate, at least in their private convictions, and closer to each other than their counterparts in the wider country. Hill staffers delight in telling stories of how their putatively extreme bosses in the House and Senate mock behind closed doors the wild rhetoric they deploy in public for audiences back home. Democrats will make protectionist noises when they need to, but my sense is that their hearts mostly arent in it; they get free trade. And Washington Monthlys Kevin Drum is on to something when he writes of a suspicion that urban conservative intellectuals  i.e., most of the ones who actually write about this stuff  are faking it when they write about socially conservative causes. Skim, say, National Review and youll find that, with the notable and humorous exception of John Derbyshire, the kind of visceral distaste for homosexuality that seems to drive grassroots activism on issues like gay marriage is largely absent; pundits there argue the conservative side mostly through tepid pseudo-sociology.

There are also shifts too recent and dramatic to explain in terms of gradual processes like migratory sorting. Consider the recently released Biennial Pew Media Survey, which tracks media consumption habits. The big trends over the past four years are the dramatic shift to cable and online news sources, as well as more ideological sorting among news outlets. Hard though it may be to believe now, only four years ago, Republicans and Democrats regularly tuned in to Fox News at about the same rate. As recently as 2000, viewership by party affiliation remained close, with 25 percent of Republicans and 23 percent of Democrats looking at the world through Rupert Murdochs eyes. But by 2004, 35 percent of Republicans decide based on what Fox reports, while Democratic viewership dropped off to 21 percent.

There are huge differences in perceptions about media venue credibility as well: Republicans are in general far more skeptical of major media reports than Democrats, but over the last four years became significantly less likely to say that they believe all or most of what they hear from CNN or the networks, while Fox News, the outlet least trusted by Democrats, became the one in which G.O.P. voters place the most faith. That divide cashes out as a significant difference in factual beliefs: A survey conducted last year by the Program on International Policy Attitudes found that viewers who count Fox as their primary news source were far more likely than others to believe that W.M.D. stockpiles had been found in Iraq, that Saddam Hussein worked closely with Al Qaeda and that world opinion supported the war.

In part, that may be a manifestation of a trend technology critic Andrew Shapiro worried about in his 1999 book The Control Revolution: As media options proliferate, we abandon the daily we of Walter Cronkites centralizing thats the way it is media space in favor of a self-reinforcing daily me we each construct by browsing through Fox News or Air America or The Nation, or, well, Reason.

But we may also be paradoxically polarized by the very consensus on big issues found by the sociologists Tierney cites in his Times article. Big clear problems  the Soviet Union, 70 percent top marginal tax rates  gave rise to Reagan Democrats and frequent aisle crossing. On the issues that genuinely divide us today, we are confused people, living in what Reason Magazine editor Nick Gillespie has called an age of uncertainty. The strictly factual debate over the justification for the war in Iraq was hugely murky for those of us without access to the intelligence purporting to show Hussein was likely to threaten the U.S. The Medicare bill was a 700-page monstrosity that has thoroughly perplexed its supposed beneficiaries. And while public ignorance is nothing new, the more uncertain the information available to each of us, the more likely we are to use heuristics like ideology or candidate personality. Consider that weve gone from a supposedly less partisan time when visions of slashing whole government agencies danced in Gingrichite heads to one in which the big debate is how much more cash to pump into a massive, unwieldy social insurance program, and when the difference between Bush and Kerry even on hugely divisive questions like Iraq can be hard to suss out.

The New Republics Jonathan Chait scarcely gives Bush a pass on the policy end, but hes confessed to bristling no less at the cowboys persona. Since, as Wooldridges observation suggests, that kind of personal animosity may be what the parties need to construct their respective political communities, the G.O.P. is probably delighted that Chait is feeling Blue.